A fuel cell is an electrochemical device made up of a fuel electrode (anode), an oxidizer electrode (cathode), an electrolyte surrounding the electrodes and supply streams for separately supplying a stream of the fuel and a stream of oxidizing agent to the anode and cathode respectively.
Conventionally, an electrocatalyst may be used in the anode and/or the cathode. During operation, fuel supplied to the anode is oxidized on the electrocatalyst in the presence of the electrolyte to release electrons. Meanwhile, the oxidizing agent supplied to the cathode is reduced on the electrocatalyst in the presence of the electrolyte while consuming the electrons supplied from the anode via an external circuit. Hence, the catalytic activity of the electrocatalyst has a vital role in the output and service life of the fuel cell.
Electrocatalysts comprising nanostructured platinum have been commonly used for the electrodes. However, the kinetic limitation for oxygen reduction reaction (ORR) when platinum is used remains a concern as the fuel cell performance is limited by the cathodic reaction, resulting in substantial loss of potential at which this reaction is taking place. Limitation of the ORR kinetics and long-term stability may arise as the platinum electrocatalysts suffer from poisoning associated with electrolytes and the hydroxyl layer. To compensate for the sluggish kinetics, undesirable high platinum loading is required for the cathode catalyst to achieve good electrocatalytic activity for ORR.
In addition, other factors such as high cost, scant availability of platinum and loss of catalytic activity due to catalyst degradation have further limited commercial applications of fuel cell technologies that rely on platinum electrocatalysts. In particular, substantial loss of electrocatalytic activity in the cathode during fuel cell operation may be attributed to the dissolution and coarsening of the platinum particles. Hence, other types of electrocatalysts have been explored to improve the performance of ORR electrocatalysts and reduce the amount of platinum needed.
One of the developments includes engineering platinum electrocatalysts by modifying platinum nanoparticles with gold clusters to enhance the catalyst durability and reduce platinum loading. Although such systems exhibit negligible activity loss between operations of 0.6V and 1.1V for more than 30,000 cycles, there was no significant improvement in the electrocatalytic activity of the gold cluster-modified platinum system. This may be because gold is not an active catalyst for the ORR in this system.
Accordingly, there is a need to provide a particle with catalytic activity that overcomes, or at least ameliorates, one or more of the disadvantages described above.
There is a need to provide a method of forming a particle exhibiting catalytic activity that overcomes, or at least ameliorates, one or more of the disadvantages described above.